Understanding Endometriosis: Causes, Fertility, and New Treatments
Endometriosis is a complex, chronic gynecological condition that affects an estimated 1 in 10 women of reproductive age. Despite its prevalence, it often goes undiagnosed or mismanaged due to the varied symptoms and the intricate nature of the disease. In this blog post, we explore the current understanding of the causes of endometriosis, its impact on fertility, and the evolving landscape of medical treatments.
What Is Endometriosis?
Endometriosis occurs when tissue similar to the lining of the uterus (the endometrium) grows outside the uterus, commonly affecting the ovaries, fallopian tubes, bladder, and bowel. This ectopic endometrial tissue behaves like normal endometrium — thickening, breaking down, and bleeding with each menstrual cycle — but has no way to exit the body. This leads to inflammation, scar tissue, and adhesions, which can result in severe pain and fertility issues.
There are three primary types of endometriosis:
Superficial peritoneal lesions
Ovarian endometriomas (chocolate cysts)
Deep infiltrating endometriosis, which can affect the rectovaginal space, bladder, and bowel
Why Does Endometriosis Cause Infertility?
The relationship between endometriosis and infertility is multifactorial and not fully understood. However, several mechanisms are believed to play a role:
Pelvic Inflammation and Oxidative Stress: Retrograde menstruation — when menstrual blood flows backward through the fallopian tubes into the pelvic cavity — may lead to blood accumulation. The iron from hemoglobin triggers oxidative stress, promoting inflammation and damaging surrounding tissue.
Altered Immune Response: Macrophages and other immune cells attempt to clean up misplaced endometrial cells but may also promote their survival and invasion.
Ovarian Reserve Damage: Endometriomas (cysts on the ovaries) and repeated surgeries can reduce the ovarian reserve — the number of viable eggs a woman has.
Progesterone Resistance: Women with endometriosis often show a reduced response to progesterone, a hormone critical for preparing the uterine lining for pregnancy.
Central Sensitisation: Chronic pelvic pain can become centralised in the nervous system, leading to ongoing pain even after the original lesions are removed.
The Impact of Endometriosis on Quality of Life
Women with endometriosis may experience:
Chronic pelvic pain
Pain during periods (dysmenorrhea)
Pain during intercourse (dyspareunia)
Fatigue
Digestive or urinary problems
Difficulty conceiving
The condition often disrupts work, social activities, sleep, and intimate relationships. Many patients report a significant reduction in quality of life.
Modern Medical Treatments: What’s New?
Traditionally, treatment for endometriosis has included pain relief, hormonal therapies, and surgery. However, recent research is reshaping the approach to managing this condition, especially for long-term care and fertility preservation.
Hormonal Therapies
Progestins (e.g. Dienogest): Suppress ovulation and menstruation, reducing lesion growth and pain. Dienogest is widely used as a first-line therapy.
Combined oral contraceptives (COCs): Regulate the cycle and reduce bleeding and pain.
GnRH antagonists (e.g. Relugolix, Linzagolix): These reduce oestrogen production to relieve pain and reduce lesion size. Some include "add-back" therapy to minimise side effects such as bone loss.
Levonorgestrel-releasing intrauterine devices (LNG-IUDs): Particularly effective for deep lesions, like rectovaginal endometriosis.
Surgical Intervention
Surgery can be helpful, particularly for deep infiltrating endometriosis or endometriomas affecting fertility. However, studies show that recurrence is common unless postoperative medical therapy is initiated.
One key takeaway: surgery should be followed by medical management to prevent recurrence unless the patient is trying to conceive immediately.
A Personalised Approach
With so many variables — severity of disease, desire for pregnancy, age, ovarian reserve, and individual symptom profile — treatment must be personalised. Current thinking suggests:
Start with hormonal therapy in most cases
Reserve surgery for severe, refractory, or fertility-compromising cases
Introduce newer agents like GnRH antagonists for women who don’t respond to first-line treatments
Use minimally invasive surgery with experienced teams to preserve fertility when required
NHS Availability in Wiltshire: What’s Funded?
If you live in Wiltshire/Bath, access to endometriosis medication is guided by the BSW (Bath and North East Somerset, Swindon and Wiltshire) Area Prescribing Committee.
Dienogest (2mg tablet) - £33 privately/month
Formulary Status: Available as a third-line treatment for endometriosis.
Restrictions: Only prescribed if oral progestogens, combined oral contraceptives, or LNG-IUD have failed or are contraindicated.
Prescribing: Must be initiated and managed by secondary care (e.g. a hospital specialist).
Relugolix-Estradiol-Norethisterone Acetate (Ryeqo®) - £114.91 privately/month
Use: For moderate to severe uterine fibroid symptoms (off-label for endometriosis may be considered in some contexts).
Status: AMBER—specialist initiation only; GPs may continue prescribing after the first month.
NHS Cost: ~£939 per year.
Linzagolix (Yselty®)
Use: NICE-approved for moderate to severe uterine fibroids. May become relevant in endometriosis care as off-label use evolves.
Status: Also AMBER—initiated by a specialist; GPs may continue.
NHS Cost: ~£1,040–£1,097 per year depending on whether hormonal add-back therapy is used.
Looking Ahead: The Future of Endometriosis Care
New drug trials are exploring combinations of hormonal and non-hormonal agents to reduce side effects while improving symptom control. Meanwhile, research into biomarkers such as microRNAs in blood and urine may lead to non-invasive diagnostic tools.
Above all, there’s growing recognition that endometriosis is a chronic condition requiring lifelong management — not a one-time fix. Education, early diagnosis, and a multidisciplinary care team are essential.
Final Thoughts
If you’re living with endometriosis, know that you’re not alone and that treatment options continue to improve. Whether your goal is pain relief, fertility, or both, there is hope — and help available. Talk to your GP or ask for referral to a specialist for individualised support.
About the Author
Dr Georgina Standen is a Women’s Health GP and Medical Director of Sirona Health. She specialises in menopause care, hormonal health, and holistic health assessments for women navigating midlife. Dr Standen combines evidence-based medicine with personalised, compassionate care.